1. Field of the Invention
The present invention relates to a digital display measuring apparatus, and particularly to such an apparatus which digitally indicates the measured length of an object based on the displacement of a contact when engaging the object.
2. Description of the Prior Art
There are well known digital display measuring systems which digitally indicate the measured length of an object. Such systems are currently utilized in various fields of engineerings and others since they eliminate any personal error in measurement and more rapidly read measurements.
In the accompanying drawings, FIG. 1 shows the outline of a prior art digital display measuring system and FIG. 2 shows the circuit diagram thereof.
Referring to FIG. 1, there is shown the measuring system which is fixedly supported by a base (not shown) at a position above an object to be measured 10, the position being determined in accordance with the size of the object 10.
The measuring system comprises an axially movable contact 12 on the body thereof. The object 10 can be measured by detecting the displacement of the contact 12 from its home position to a position in which the contact 12 engages the object 10.
To detect the displacement of the contact 12, there is provided an encoder 14 which may be of any conventional type such as photoconductive type, electrostatic capacity type, variable resistance type or the like. The encoder 14 is adapted to convert the displacement of the contact 12 into an electrical sine-wave signal.
The electrical signal from the encoder 14 is converted into pulses through a waveform processing circuit (not shown). The pulses are then counted by a counter circuit 16 with the counted value being digitally indicated at an indicator section 20 on a digital display 18.
Thus, the indicator section 20 of the digital display 18 normally indicates a measurement corresponding to the displacement of the contact 12. Maximum measurement to be indicated will be restricted by the displacement of the contact 12. Therefore, the digital display 18 cannot indicate the measured length of an object which exceeds the maximum displacement of the contact 12.